Area of right triangle = (1/2)(BC ) (BA) (1)
Two white areas that are between the gray areas and triangle ABC = area of semi-circles - area of ABC =
(1/2) [ pi (AC/2)^2 - (BC)(BA) ] = (1/2) [ pi ( BC^2 + BA^2)/4 - (BC)(BA) ] (2)
Area of grey semi-circles = (1/2)pi [ (BC/2)^2 + ( BA/2)^2 ] - (2) =
(1/2) pi [ (BC^2 + BA^2)/4 ] - (1/2) [ pi (BC^2 + BA^2)/4 - (BC)(BA) ] =
-(1/2) [ - (BC)(BA) ] =
(1/2)(BC)(BA) which = (1)
So....true !!!